A goal of pharmaceutics is to efficiently deliver a therapeutic drug to the site of action. Over the years methods have been developed to achieve this goal.
One approach to the drug delivery improvement is to use a formulation which is liquid at room temperature but which forms a semi-solid when warmed to body temperature.
Such a system hs been described in U.S. Pat. No. 4,188,373 using "Pluronic.RTM. polyols" as the thermally gelling polymer. In this system the concentration of polymer is adjusted to give the desired sol-gel transition temperature, that is the lower concentration of polymer gives a higher sol-gel transition temperature. However, with the currently commercially available "Pluronic.RTM." polymers the ability to obtain a gel of the desired rigidity is limited while maintaining the desired sol-gel transition temperature at physiologically useful temperature ranges near 26.degree.-35.degree. C.
Similarly a Canadian patent 1,072,413 which relates to (poloxamer polyols) with gelling temperatures higher than room temperature uses additives to bring about the gelling characteristics of the polymer which contains therapeutic or other type agents. Also in this Canadian patent "Tetronic.RTM." polymers are used as additive agents rather than the primary polymeric agent as in the instant case.